While I think the girlfriend's skills were overstated, as to the black walnuts.
Throw them out in the lane and drive over them until the husks are off, then gather and crack them, a sturdy pliers will do. Don't expect much.. Lots of work, little reward! A job best done in the depth of winter, involving alcohol, boredom and resolve.
Generally we turned the sows out in the grove in the fall, pigs can shell them nicely.
And indeed, black walnut will make some great stocks!

Chief